Volcanic ash heading to the UK

Please see comment from Professor Bill McGuire, professor at the Aon Benfield UCL Hazard Research Centre, on the cloud of ash from Iceland’s erupting Eyjafjöll volcano heading towards the UK, causing major disruption to UK domestic air traffic.

BackgroundThe 1600 meter high Eyjafjöll volcano (also known as Eyjafjallajökull) is located in southern Iceland, immediately west of Katla volcano. Eyjafjöll is an elongated, ice-covered volcano topped by a 2.5 kilometre wide summit caldera. The volcano appears to have been relatively inactive over the last 10,000 years, and the sole historical eruption, prior to this year, occurred in 1821.

The current eruption started on 20 March 2010. Following a pause in activity, a new vent opened on 13 April generating a column of ash several kilometres high and causing melting of overlying glacier ice. This resulted in the formation of glacial outburst floods that closed roads and caused some structural damage. Around 700 people were evacuated from the area as a precaution.

The ash cloud generated by the ongoing eruption is currently to the north of Scotland, and heading south at a height of about 18 km. It is currently expected to move across Scotland and northern England by 13.00 BST, April 15. As of 10.00, Scottish and northern airports are closed and London’s airports are expected to close later in the day.

The threatVolcanic ash is silica-based material and highly abrasive. It is capable of causing major damage to aircraft through clogging engines causing them to flame out and by scouring windscreens making them opaque.

Over the past few decades there have been more than 80 encounters between civil aircraft and ash clouds, resulting in a number of situations wherein crashes have only narrowly been avoided.

Most notable was an encounter in 1982 between a BA 747 and an ash cloud from Galunggung volcano in Indonesia. Ash resulted in all four engines failing, causing the plane to fall 7,000m before the engines could be restarted. Even then, landing was made extremely difficult because the windscreen had been scoured opaque by the ash.

FrequencyIt is not particularly unusual for ash from Icelandic eruptions to reach the UK. The most notable occasion occurred in 1783, when a cloud of ash and sulphurous gases from the major Laki eruption lay across Europe from the summer of that year and into 1784.

The cloud resulted in elevated summer temperatures and resulted in poor air quality that caused a significant increase in mortality in the UK and elsewhere in Europe. Such a large eruption occurring today would have the potential to severely affect air travel at high northern latitudes for six months or more. In relation to the current eruption, it is worth noting that the last eruption of Eyjafjöll lasted more than 12 months. If this eruption has a similar duration then ash could periodically present a problem in UK air space.